hardware:: tag matching lib plans

[Michael Vogt]

On Fri, Jan 20, 2012 at 12:43:43PM +0100, Enrico Zini wrote:
> On Mon, Jan 16, 2012 at 04:39:52PM +0100, Michael Vogt wrote:
> 
> > > I like the idea. In fact, the whole hardware::* tag could be managed by
> > > the maintainers of the detection library, effectively as part of that
> > > project. The two things will give each other meaning.
> > 
> > Cool idea! The project is still in the infant stage but some stuff
> > appears to be working already. My initial goal would be to cover the
> > current tags plus additional meaning like "requires writer" that are
> > combinations of tags (like you outlined below).
> 
> Would you like to add the code to the debtags package[1]?
> 
> I've recently started to add python scripts to it (see
> debtags-submit-patch and debtags-fetch), and this whole thing calls for
> a "debtags-hardware" script that would output the hardware detection
> results.

Thanks! That makes indeed perfect sense given how closely the hw
debtags and the lib needs to be coupled. I will prepare a branch for
it. 

Cheers,
 Michael
 
> [1] ssh://git.debian.org/git/debtags/debtags.git
> 
> 
> > > > Tag: hardware::storage:cd:writer
> > > > Description: Compact Disc writer
> > > > (or hardware::storage:cd-writer ?)
> > > > 
> > > > Tag: hardware::storage:dvd:writer
> > > > Description: Digital Versatile Disc writer
> > > 
> > > This is something that I would prefer to get via a combination of
> > > different tags: use::viewing/use::editing, for example, to distinguish
> > > between cd/dvd players and cd/dvd writers. If that strategy gives
> > > wrong results, then we can consider adding special tags.
> > 
> > Nice! Yeah, I can certainly change the code in the lib to look at the
> > use:: tag and check for CD/CD-writer depending on it.
> 
> Cool. I reckon the results would need to output both positive and
> negative matches. Something like:
> 
>  ok: hardware::storage:dvd, use::viewing
>    + found DVD reader "Pioneextor Fasturbo 42x" at /dev/scd0
>  no: hardware::storage:dvd, use::editing
> 
> I think you need both to be able to give proper hints, otherwise the
> hinter wouldn't know if a hardware tag combination isn't supported by
> the system, or of instead it's just a combination that the checker
> doesn't check for.
> 
> 
> > > Things could be fixed by putting tags in debian/control, at some point.
> > > It could be time to reevaluate that option, but even if we started
> > > working on that now, I don't think it's going to happen before at least
> > > 6 months.
> > 
> > Thanks! I'm not very concerned about it at this point but its good to
> > keep it in mind. As a workaround we still could add XB-Tag to the
> > debian/control file, couldn't we? Or will that cause other problems?
> 
> We could, I'm starting to think of a strategy for that that would also
> address the requirement I have from maintainers to be able to say "I'd
> like to declare these tags of my packages as 'stable'".
> 
> I'll think a bit more about it, then send out a proper proposal.
> 
> 
> > > The other issue I see is that the logic isn't very extensible: if
> > > tomorrow you need to track another hardware feature that requires a <=
> > > or >= comparison and not just an 'has tag' one, then you're stuck. OTOH,
> > > if such needs arise, then it's time to design a specially crafted
> > > control file header, but at least tags took us to that point.
> > 
> > Thanks again! I would prefer not to use special headers as we have
> > enough of them already and debtags feels to me like a much nicer and
> > more general solution.
> > 
> > I'm not quite sure I understand the limitation here correctly. At
> > least for the memory case it could work like this:
> >  Ceck if HW requirements are meet by building up a search that
> >  include hardware::memory:1GB if the machine has at least 1GB
> >  memory. When checking the requirements it would iterate the tags and
> >  simply parse the value when it finds "hardware::memory:" and compare
> >  it. For a query it could add some tags based on the HW  (at startup
> >  or when building the query) or possible using a xapian KeyMaker
> >  (probably not very fast when python is used though). Not very
> >  granular, as it would probably just {0.5,1,2,4} GB initially and a
> >  machine with 4g would simply include a or-query with all of those values. 
> > 
> > Or would that be considered ugly? 
> 
> Alternatively, with negative hints, packages can have tags like:
> 
>   hardware::memory:2GB  # 2GB or more
>   hardware::memory:4GB  # 4GB or more
>   hardware::memory:8GB  # 8GB or more
> 
> for which the hardware detection code can produce negative matches:
> 
>   ok: hardware::memory:2GB+
>     + found 2GB RAM, 1GB swap
>   no: hardware::memory:4GB+
>   no: hardware::memory:8GB+
> 
> > > More ideas for hardware tags can come from looking at:
> > > http://debtags.debian.net/edit/tags/hardware::TODO
> > > (I'm sorry it it still misses a 'next page' option)
> > 
> > Very nice, thanks! Looks like bluetooth and wifi are obvious
> > candidates from looking over the list (and maybe firewire 1394 but I
> > don't know much about that myself).
> 
> Bluetooth was easy: added:
> 
>  Tag: hardware::bluetooth
>  Description: Bluetooth
> 
> Wrt wifi, I don't know the technology well enough: should we just do
> hardware::wifi, or is there already a need to distinguish a, b, g, n or
> whatever thing they'll come out with this year?
> 
> My gut feeling would be to avoid going into that kind of detail, but
> maybe for practical purposes it makes strong sense to do it and I just
> am not aware of it.
> 
> 
> Ciao,
> 
> Enrico
> 
> -- 
> GPG key: 4096R/E7AD5568 2009-05-08 Enrico Zini <enrico at enricozini.org>



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